Seal for circuit controlling devices



Dec. '23, 1941. L N 2,267,364

SEAL FOR CIRCUIT CONTROLLING DEVICES Filed 001;. 14, 1939 IN l/E N TOR A T ORNE) MBLOUNT- BY Patented Dec. 23, 1941 stars s PAT ENT: F F 10, E

I 7 267,364, V SEAL-FOR: CIRCUIT CONTROLLING EVICES Nelson Bi Du, 12,. MflI!lBwood, J assign: to Ben Tel nhsme b rato Incorporated, New

or like corp r n, of Newi qrk Anplicationflctober 14, 1939, Serial No. 299,450

,2 cl ims, (Cl. 286F129) Ihis invention relates to circuit controllingida vices and more particularlytopush button switches especially: suitable for use in telephone instruments, such asireceiv-ers; transmitters and immediate vicinity oi the instrument for control ling the associationordisassociation of the instrument. with a telephone line. In a. number of instances the instrument is used in exposed locations, as; for example, on ships, where it is exposed to high moisture content atmospheres, may be subjected to spray, or may even be immersed in water, whereby the elements of the switch itself and especially the contacts or springs become corroded and the proper operation of the switch is impaired or prevented.

One object of this invention is to prevent impairment of the operation of circuit controlling devices used in exposed locations.

Another object of this invention is to simplify the construction of push button switches for telephone instruments.

In one illustrative embodiment of this invention, a push button switch comprises a, housing,

wherein contact springsare mounted, having a tion, the shank is encompassed by a resilient spool, for example, of rubber, which has a tubular portion fitted about the shank, and flanged end portions, one of which abuts the head of the push button or plunger and the other of which abuts the outer wall of the casing. The resilient spool may be slightly compressed initially and forms a water-tight and moistureproof seal between the casing and the push button or plunger.

The invention and the foregoing and other features thereof will be understood more clearly and fully from the following detailed description with reference to the accompanying drawing wherein:

Fig. 1 is a side View mainly in section of a telephone instrument including a push button switch constructed in accordance with this invention, and

Fig. 2 is a partial cross-sectional view along instrument comprises a cup-shaped casing l 0, forexample, of insulating material, having in the face thereof an annularseat It in which a resilient sealing washer I2 is fitted,- Seated upon I the sealing washer I2 is atelephone uni-t l3 which is securely clampedin position by an apertured cap l4 threaded to the casing l0. 1 The telephone unit may be a transmitter or receiver, for example, of the construction disclosed in the application, Serial No. 93,792; filedAugust 1,1936, of Louis A. Morrison and Edward E. Mott, now Patent No, 2,220,942, issued November 12, 1940, and comprises-a pair of spacedor coaxialterminals l5 and I6.

Mounted within the casing I 0 are a plurality of contact springs ll, l8, l9 and 20, which are insulated from one another and are fixed in position as by screws 2! extending through insulating sleeves 22 and threaded into nuts 23 embedded in the casing l0. As shown clearly on Fig. 2, the spring l1 engages the terminal I 6, the spring I8 is adapted to engage the terminal I5 and the springs l9 and 2!) are adapted to engage each other at contact points 24. The spring I9 carries an insulating button 25 engaging the spring I'B. Electrical connection to the several contact springs may be established through a multiconductor cord, not shown, which extends through a coupling 26, a moisture and water-tight seal between the cord and coupling being formed by a compressible sealing member 21, for example, a rubber ring.

The casing I0 is provided in its outer surface with a recess 28 and with an aperture or bore extending from the recess 28 to the inner wall of the casing. Extending through this bore or aperture is the shank 29 of a reciprocable plunger or push button having a, head portion 30 provided with a depending portion 3| telescopically fitted in the recess 28. The shank 29 is encompassed by the tubular sleeve portion 32 of a resilient, for example, rubber, spool having end flange portions 33 abutting the base wall of the recess 28 and the head portion 30 of the push button, the sleeve portion 32 preferably being fitted on the shank 29. If desired, the flanges 33 may be secured, as by cement, to the base wall of the recess 28 and the head portion 30 of the push button. The sleeve portion 32 of the spool is encompassed by a coiled spring 34, opposite ends of which bear against the flanges 33.

The push button, as shown, may be of metal and provided at its inner end with an insulating gloltton 35 adapted to engage the contact spring The normal position of the push button may be fixed by a suitable stop, such as a pin 36, extending through the shaft 29, adapted to engage the inner Wall of the casing l0. Preferably, the pin 36 is so located that the spring 34 and spool 32, 33 are under an initial compression whereby the flanges 33 are firmly pressed against the base wall of the recess 28 and the head 30 of the push button and the sleeve portion 32 is compressed about the shank 29. When the push button is depressed, the firmness of the engagement be tween the elements of the push button and casing and the associated parts of the spool will be increased. 7

It will be noted that at all times the sleeve 32 is in firm engagement with the shank 29 and the flanges 33 are in firm engagementwith the base wall of the recess 28 and the head 30 of the push button so that water-tight and moisture.-

proof seals are formed between these elements;

Consequently, entrance of moisture into the easing and attendant deterioration of the contact springs and other internal elements is prevented.

Although a specific embodiment of this invention has been shown and described, it will be understood, of course, that it is but illustrative and that various modifications may be made therein without departing from the scope and spirit of this invention as defined in the appended claims.

What is claimed is:

1. In combination, a casing having an aperture therein and having a seating surface on an outer surface portion thereof adjacent said aperture, a reciprocable plunger member having a shank extending through said aperture and slidable therein, said plunger member having also a portion provided with a seating surface facing said first surface, and means defining a moistureproof seal between said casing and reciprocable member including a resilient member having a sleeve portion encompassing and firmly engaging said shank of said reciprocable member and having also flange portions at opposite ends of said sleeve portion and in sealing engagement with said seating surfaces.

2. In combination, a casing having an aperture in one Wall thereof and having also a recess in the outer portion thereof and in communication with said aperture, a reciprocable plunger having a shank slidably fitted in said aperture and having also an enlarged head portion telescopically fitted in said recess, a resilient spool having a sleeve portion fitted on said shank and having also end flange portions, one of which is in face to face engagement with the base wall of said recess and the other of which is in face to face engagement with the surface of said head portion toward the base wall of said recess, a helical spring encompassing said sleeve portion and having its ends bearing against said flange p0rtions, and means in cooperative relation with said casing and said reciprocable member for maintaining said spool and spring under compression.

NELSON BLOUNT. 

